Strain relieved thin wire two part connector

ABSTRACT

The invention is concerned with relieving connections formed with fine wires (e.g., of 0.08 mm diameter), of strain caused by an axial tension imposed on the wires during handling. To achieve this, the wire is wound around a portion of insulating body after connection to a tab carried by the body, and is retained in position around the body by inserting the portion in a troughlike portion formed on another insulating body. The one insulating body is provided with a socket retaining a contact member electrically connected to the tab and the other is provided with a post of conductive material which is inserted into the socket to make electrical connection to the contact member on insertion of the one body into the other body.

United States Patent 1191 Teagno et al.

1 STRAIN RELIEVED THIN WIRE TWO PART CONNECTOR [22] Filed: Dec. 3, 1971[21] Appl. No.: 204,525

[30] Foreign Application Priority Data Belgium 339/176 M Oct. 9, 19733/1970 Great Britain 339/217 S 459,609 l/l937 Great Britain 339/105Primary Examiner-Marvin A. Champion Assistant Examiner-Lawrence J. StaabAttorney-William J. Keating et a1.

[57] ABSTRACT The invention is concerned with relieving connectionsformed with fine wires (e.g., of 0.08 mm diameter), of strain caused byan axial tension imposed on the wires during handling. To achieve this,the wire is wound around a portion of insulating body after connectionto a tab carried by the body, and is'retainedin position around the bodyby inserting the portion in a trough-like portion formed on anotherinsulating body. The one insulating body is provided with a socketretaining a contact member electrically connected to the tab and theother is provided with a post of conductive material which is insertedinto the socket to make electrical connection to the contact member oninsertion of the one body into theother body.

5 Claims, 8 Drawing Figures PATENTEDBBT 91m 7 3.764.958

SHEET 10F 5 'PATENTEDUET ems SHEET [1F 5 STRAIN RELIEVED THIN WIRE TWOPART CONNECTOR The invention relates to an electrical connector for thinwire, typically having a diameter of the order of 0.08 mm, used in verysmall electrical units accessory to main circuitry, for example magneticcore assemblies of logic circuits for detachably mounting on a printedcircuit board of a computer or detachable parts of micro-electromagnetsof microswitches. Such connectors must be very small, for example thelength of a bank of ten connectors may be as small as '1 cm, while itstransverse cross-section size may be as small as .1 sq. mm. The thinwire in question has very low mechanical strength and considerable careis required in handling the wire to avoid breaking it. Extra care isrequired in handling connections formed of such wire and otherelectrical conductors, for example connections formed by soldering thewire to a conductive path of a printed circuit board, since the wire isweakened, as by deformation or fusion, in making the connection. Thereis thus a need to relieve strain imposed on such a connection by anaxial pull on the thin wire.

The invention provides an electrical connector for thin wire comprisingfirst and secondinterengageable elongate insulating blocks, the firstblock being of trough-like transversecross-section and having a seriesof posts of conductive material extending through, and outstanding from,opposite faces of the base of the trough at intervals along its length,the blocks being engageable by insertion of the second block into thetrough of the first block in a free fit; the second block being formedat corresponding intervals along its lower side with a series ofpost-receiving sockets and having a corresponding number of tabs ofconductive material upstanding from its upper side, each socketretaining a contact member electrically connected to an individual taband arranged to effect electrical connection to a post on insertion ofthe second block, the arrangement being such that on engagement of theblocks a fine wire electrically connected at one end to the tab andpassed transversely around the second block with its free end extendingaway from the upper side of the second block will be retained locatedaround the block thereby to relieve the connection of tension forcesapplied to the free endof. the wire.

parallel to each slot 7. On one side the slot 8, best seen in FIG. 6,extends longitudinally of the block a slight distance towards anadjacent cavity 6 and at the other side a shoulder 9, FIG. 7, extendsoutwardly of the top of the slot. Wire-receiving grooves of V-sectionextend through the height of the side wall 5 between adjacent slots 7and each communicate with another such The invention will be describedby way of example with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of part of a one block having one contactto which an end of a wire has been soldered;

FIG. 2 is a perspective view of the contact of FIG. 1 integral with acarrier strip;

FIG. 3 is a perspective view of part of a second block;

FIG. 4 is an underplan view of the block of FIG. 1;

FIG. 5 is a longitudinal sectional view along line V-V of FIG. 4;

FIG. 6 is a cross-sectional'view along line VI-VI of FIG. 4;

FIG. 7 is a cross-sectional view along line VII-VII of FIG. 4; and

FIG. 8 is a cross-sectional view along line VIII-VIII of FIG. 4.

One block 1 of FIGS. 1 and 6 to 8 comprises an elongate molding ofinsulating material having a top wall 2, a bottom wall 3 and oppositeside walls 4, 5. Contactreceiving cavities 6 are spaced apartlongitudinally of groove. 11 which extends transversely of the bottomwall 3 and opens in the respective wider slot 8 in the side wall 4. Ascan beseen in FIG. 8, the groove 10 and the floor of the slot 8 arecurved. An L-shaped latch 12 extends laterally outwardly from the topwall 2 adjacent the upper end of each groove 10 and has a retaining arm13 adjacent the upper mouth of the groove. Each slot 7 communicates withthe lower portion of the respective slot 8 transversely of the block Ithrough a passageway 14. The wall of the passageway 14 remote from therespectivegroove 10 is generally flat but the lower edge is inclinedoutwardly at 15, as best seen in FIG. 5. The opposite wall of thepassageway 14 has a cavity opening in the top wall 2, the cavity havingthree straight sides 16 and a floor defining a ledge 17, best seen inFIG. 8.

Each cavity 6 has a contact 18, best seen in FIG. 2. The contact isformed with others, not shown, in strip form of resilient metal, forexample phosphor bronze,

and comprises a terminal post 19 having at its upper end a V-slot 20 forsolder connection to a thin wire. The lower end of the post 19 has anarch-shaped hole 21 and a lateral extension 22 which has oppositelateral extensions 23, 24 adjacent its free end 25. As shown, the upperextension 23 comprises a spring blade which is bent upon itself so thatthe blade free end 26 of the extension 23 is in spaced relation from thebody of the blade. The lower extension 24 isbent so that the free end 27integral with a carrier strip is directed towards the plane of theextension 22. In anothericonstruction, not shown, the lower extension22has, the spring blade. The lateral extension 22 is bent generallynormal to the plane of the post 19. at 28, as shown.

The spring blade of each contact 18 is received in a respective cavity 6by reception of the lateral extension 22 in the respective passageway14. As the extension 22 is moved inwardly of the passageway 14 thespring blade23 is compressed inwardly until it reaches a wall 16 when itsprings out so that the free end 26 engages the ledge 17, as seen inFIG. 5. In this condition the lower portion of the post 19 of thecontact 18 is received in the slot 8 with the upper portion standingproud of the block 1, and the arch-shaped hole 21 overlies the adjacentend of the groove 11. The spring blade of the contact 18 is retained inthe cavity 6 by abutment of the post 19 and the base of the slot 4 whichprevents further movement of the extension 22 longitudinally inwardly ofthe passageway 14, the opposite sides 17 and the sides of the springblade 23 which prevent movement in the reverse direction and theshoulder 9 which prevents tilting movement of the post 19.

The one block 1 having contacts 18 is received in a channel-shapedsecond block 29 of the FIG. 3, having a base 30 and opposite side walls31, 32. The base 30 contains posts 33 received in the through-holes,.not

shown, having end portions projecting below the base for reception inthrough-holes 34 in a printed circuit board 35, conveniently associatedwith a computer. One side wall 31, has depressions 36 extending theheight of the walls and spaced apart the distance separating adjacentposts 19 of the one block 1. The upper edges 37 of the depressions 36are chamfered, as shown, and the intervening wall parts 38 are smooth.

In use, an end of a thin self-soldering enamelled wire 39 of FIG. 1, forexample one having a diameter of the order of 0.08 mm is received in theslot 20 of a respective post 19 and then passed down the outside of thepost 19 into the grooves 11 and 10 and then upwardly away from the sidewall 5 of the one block 1. The wire 39 is held in the groove by thelatch 12. The end of the wire 39 is soldered to the post 19. Similarconnections are made to other posts. The second block 29 is located onthe printed circuit board 35 by reception of the lower portion ofterminal posts 33 in respective holes 34 of the board and the one block1 is then inserted into the second block 29 with the shoulders 9 of theblock 1 received in the depressions 36 and the posts 19 abutted againstthe wall parts 38 with the wire 39 wedged therebetween. As can be seenin FIG. 8, the soldered joint is strain relieved because of the frictionengagement of the wire 39 with the posts 19 and the wall 33 and with thewalls of the grooves 11 and 10. The upper portion of the posts 33 of theblock 29 are received in the cavities 6 and compress the spring blades23 which act as beam springs being trapped at the root integral with thelateral extension 22 and 25 and at the free end 26 in abutment with thewall 16. In this way electrical connection is established between theposts 19 and conductive paths of the printed circuit board.

The one block 1 may be separated from the second block 29, using a toolhaving jaw parts adapted to engage end shoulders 40, FIG. 5. Thecontacts may be changed by desoldering the wire 39 from the respectivepost 19 which may then be separated from the respective cavity 6 byurging the free end 26 away from the ledge 17 using a screwdriver bladeinserted in the cavity from the top wall 2.

In another arrangement, not shown, the terminal post 19 is smaller thanthe slot 8 longitudinally of the block and a wire 39 passed through thearch-shaped hole 21 is passed up the post at an angle to the verticalplane. The post may have shoulders adapted to abut the upper surface ofthe one block, and the spring blade may be formed on the lower extension22.

We claim:

1. An electrical connector for thin wire comprising first and secondinterengageable elongate insulating blocks, the first block being oftrough-like transverse cross-section and having a series of posts ofconductive material extending through and outstanding from oppositefaces of the base of the trough at intervals along its length, theblocks being engageable by insertion of the second block into the troughof the first block in a free fit; the second block being formed atcorresponding intervals along its lower side with a series ofpostreceiving sockets and having a corresponding number of tabs ofconductive material upstanding from its upper side, each socketretaining a contact member electrically connected to an individual taband arranged to effect electrical connection to a post on insertion ofthe second block, the second block having first and second opposedsidewalls and a bottom, the tabs extending upwardly along the firstsidewall, wire guiding grooves disposed in the bottom and secondsidewall of the second block, the grooves being aligned with the tabs,the arrangement being such that on engagement of the blocks the tabs lieclosely adjacent a side of the trough of the first block, and a finewire electrically connected at one end to the tab and passed between atab and the adjacent side of the trough and transversely around thesecond block in the wire guiding grooves with its free end extendingaway from the upper side of the second block will be retained locatedaround the block thereby to relieve the connection of tension forcesapplied to the free end of the wire.

2. An electrical connector according to claim 1, wherein the contactmembers and tabs are each integrally formed from a sheet metal blank andeach contact member has a contact portion comprising a resilientlyflexible blade.

3. An electrical connector according to claim 2, wherein each contactmember is insertable into its socket and includes a resiliently flexiblelocking tongue which is flexed during such insertion and snaps intoengagement with an abutment surface formed in the block to lock themember in the socket.

4. An electrical connector according to claim 3, wherein the lockingtongue is constituted by an extension of the blade.

5. An electrical connector according to claim 4 wherein a hook portionis formed adjacent the wire guiding groove disposed in the secondsidewall of the second block and at the upper end thereof to retain thewires in the grooves.

1. An electrical connector for thin wire comprising first and secondinterengageable elongate insulating blocks, the first block being oftrough-like transverse cross-section and having a series of posts ofconductive material extending through and outstanding from oppositefaces of the base of the trough at intervals along its length, theblocks being engageable by insertion of the second block into the troughof the first block in a free fit; the second block being formed atcorresponding intervals along its lower side with a series ofpost-receiving sockets and having a corresponding number of tabs ofconductive material upstanding from its upper side, each socketretaining a contact member electrically connected to an individual taband arranged to effect electrical connection to a post on insertion ofthe second block, the second block having first and second opposedsidewalls and a bottom, the tabs extending upwardly along the firstsidewall, wire guiding grooves disposed in the bottom and secondsidewall of the second block, the grooves being aligned with the tabs,the arrangement being such that on enGagement of the blocks the tabs lieclosely adjacent a side of the trough of the first block, and a finewire electrically connected at one end to the tab and passed between atab and the adjacent side of the trough and transversely around thesecond block in the wire guiding grooves with its free end extendingaway from the upper side of the second block will be retained locatedaround the block thereby to relieve the connection of tension forcesapplied to the free end of the wire.
 2. An electrical connectoraccording to claim 1, wherein the contact members and tabs are eachintegrally formed from a sheet metal blank and each contact member has acontact portion comprising a resiliently flexible blade.
 3. Anelectrical connector according to claim 2, wherein each contact memberis insertable into its socket and includes a resiliently flexiblelocking tongue which is flexed during such insertion and snaps intoengagement with an abutment surface formed in the block to lock themember in the socket.
 4. An electrical connector according to claim 3,wherein the locking tongue is constituted by an extension of the blade.5. An electrical connector according to claim 4 wherein a hook portionis formed adjacent the wire guiding groove disposed in the secondsidewall of the second block and at the upper end thereof to retain thewires in the grooves.